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| United States Patent |
6,136,397
|
|
Luhmann
, et al.
|
October 24, 2000
|
Redetachable, self-adhesive device
Abstract
Redetachable, self-adhesive device having a plate, the sides and/or front
side of which have fastening means, if appropriate, and the rear side of
which has a strip of an adhesive film which is adhesive on both sides and
is adhesively attached in such a way that one end of the adhesive film
protrudes beyond the plate as a grip, the adhesive film being of such a
kind that the adhesive bond achieved with it can be released again by
pulling, stretching the strip, characterized in that the plate (1) has at
its end, or on its rear side (2) at least in the region (3A, 3B) which
bears against the grip (6) of the adhesive film strip (5), low stick and
slip friction with respect to the adhesive film strip (5).
| Inventors:
|
Luhmann; Bernd (Norderstedt, DE);
Junghans; Andreas (Hamburg, DE)
|
| Assignee:
|
Beiersdorf AG (Hamburg, DE)
|
| Appl. No.:
|
927754 |
| Filed:
|
September 11, 1997 |
Foreign Application Priority Data
| Sep 13, 1996[DE] | 196 37 222 |
| Jul 11, 1997[DE] | 197 29 706 |
| Current U.S. Class: |
428/40.1; 248/467; 248/683; 428/40.2; 428/41.3; 428/41.8; 428/42.1; 428/100; 428/192; 428/194; 428/421 |
| Intern'l Class: |
C09J 007/02 |
| Field of Search: |
428/40.1,40.2,41.3,41.8,42.1,192,194,100,67,421
248/467,683
|
References Cited
U.S. Patent Documents
| 5516581 | May., 1996 | Kreckel | 428/343.
|
| 5672402 | Sep., 1997 | Kreckel | 428/343.
|
Primary Examiner: Ahmad; Nasser
Attorney, Agent or Firm: Norris, McLaughlin & Marcus, P.A.
Claims
We claim:
1. A redetachable, self-adhesive device comprising:
a) a plate having a front, a rear and four sides;
b) a double-sided adhesive strip of film adhered to the rear of said plate
through an adhesive bond in such a way that one end of said adhesive film
strip protrudes from said plate as a grip; and
c) optionally one or more fasteners protruding from the sides or front of
said plate for fastening said plate to another device;
wherein
the adhesive bond between said adhesive film strip and said plate can be
released by pulling and stretching the adhesive film strip; and
the plate has at its end which bears against the grip of said adhesive film
strip or on its rear at least in a region which bears against the grip of
said adhesive film strip, a plastic surface formed from a polymer selected
from the group consisting of fluorine-containing polymers, organo-silicon
polymers, polyolefins, polymers which contain fluorine-containing
segments, organo-silicon polymer segments or polyolefin segments, and
polymers based on mixtures of the aforementioned polymers.
2. Device according to claim 1, wherein that the stripping force at a
pulling-off angle of 60.degree. is no more than three times.
3. Device according to claim 1, wherein the stripping force at a
pulling-off angle of 90.degree. is no more than three times.
4. Device according to claim 1, wherein the region which bears against the
grip allows with respect to the adhesive film strip a stripping force at a
pulling-off angle of 60.degree. which is three times the stripping force
at the pulling-off angle of 0.degree..
5. Device according to claim 1, wherein the region which bears against the
grip allows with respect to the adhesive film strip a stripping force at a
pulling-off angle of 90.degree. which is three times the stripping force
at the pulling-off angle of 0.degree..
6. Device according to claim 1, wherein the region which bears against the
grip has a surface tension of up to 37 mN/m.
7. Device according to claim 1, wherein the region which bears against the
grip is formed together with the plate as an integrated injection-moulded
part of plastic.
8. Device according to claim 1, wherein the adhesive film, with or without
an intermediate substrate, is elastically or plastically extensible.
9. Device according to claim 1, wherein the adhesion of the adhesive strip
is less than the cohesion, the adhesion is to a great extent dissipated
when the film is extended, and the ratio of pulling-off force to tearing
load is at least 1:2.0, the adhesive film strip being of the kind which is
based on thermoplastic rubber and tackifying resins.
10. Device according to claim 1, wherein the rear side of the adhesive film
strip is covered with a release laminate.
11. Device according to claim 1, wherein there is a hook on the front side
of the plate.
12. Device according to claim 1, wherein the plate has on its rear side
laterally alongside the adhesively attached adhesive film strip spacers
(8A, 8B), the height of which is less than the thickness of the adhesive
film strip.
13. Device according to claim 12, wherein the spacers are located on both
sides alongside the adhesively attached adhesive film strip.
14. Device according to claim 12, wherein the spacers are formed as fillets
or segments.
15. Device according to claim 12, wherein the spacers are formed together
with the plate as an injection-moulded part.
16. Device according to claim 12, wherein the height of the spacers is
30-90% of the thickness of the adhesively attached adhesive film strip.
17. Device according to claim 2, wherein the stripping force at a
pulling-off angle of 60.degree. is no more than two times the stripping
force at a peeling-off angle of 0.degree..
18. Device according to claim 3, wherein the stripping force at a
pulling-off angle of 90.degree. is no more than two times the stripping
force at a peeling-off angle of 0.degree..
19. Device according to claim 4, wherein the region which bears against the
grip allows with respect to the adhesive film strip a stripping force at a
pulling-off angle of 60.degree. which is two times the stripping force at
the pulling-off angle 0.degree..
20. Device according to claim 5, wherein the region which bears against the
grip allows with respect to the adhesive film strip a stripping force at a
pulling-off angle of 90.degree. which is two times the stripping force at
the pulling-off angle 0.degree..
21. Device according to claim 10, wherein the release laminate is a
siliconized release paper or a release film.
22. Device according to claim 16, wherein the height of the spacers is
0.3-0.6 mm and the thickness of the adhesive film strip is 0.65 mm.
23. A method of forming a temporary bond between a substrate and device
according to any one of claims 2-5, 16 and 17-20, 21 and 22, said method
comprising adhering said device to said substrate by means an adhesive
bond formed between said substrate and said adhesive film strip, and
thereafter releasing said device from said substrate by pulling on the
grip of said adhesive film strip at an angle approximately perpendicular
to the plane of the bond formed between said substrate and said adhesive
film strip.
24. The method according to claim 23, wherein said device is released from
said substrate by pulling on the grip of said adhesive film strip at an
angle of 45.degree.-135.degree. relative to said bond plane.
Description
BACKGROUND OF THE INVENTION
1. Field of the Invention
The invention relates to a redetachable, self-adhesive device which can be
released again from its adhesive bond without leaving any residue by
pulling on the adhesive film arranged on it.
2. Description of Related Art
Such devices, in particular hooks, are known. For instance, DE 42 33 872 C2
describes a redetachable, self-adhesive hook which is equipped with an
adhesive film which can be adhesively released by pulling and which is
commercially available as "tesa.RTM. Power-Strips with Hooks". A so-called
system hook with base plate and attachable decorative hook is also
commercially available as the "tesa.RTM. Power-Strip System Hook".
WO 94/21157 also discloses such a hook, which differs from the
abovementioned hook in particular by the use of an adhesive film of the
kind which is highly extensible and at the same time does not recover its
original form.
In the practical use of such devices, problems may occur, however, in
particular during later detachment. This is so since a re-releasable
adhesive bond is achieved in all the abovementioned cases by a stretching
of the self-adhesive tape used for the adhesive bonding and provided on
one or both sides with a contact adhesive. For this purpose, starting from
a grip, the adhesive tape is pulled in the direction of the grip
substantially parallel to the bonding plane. The extension of the adhesive
tape which is produced causes it to be released from the underlying
surface without leaving any residue. WO 92/11332, WO 92/11333, WO 94/21157
and WO 95/06691 specify as the maximum pulling-off angle for redetachment
without leaving any residue an angle of 35.degree. between the bonding
plane and the extending direction. In addition to high extensibility, a
low offset yield stress in the case of low to moderate extensions combined
with an adequately high tearing resistance in the case of high extensions
are important for releasing the adhesive tape from an adhesive joint
completely and without leaving any residue. For a reliable detachment
process, the tearing resistance must in this case be well above the force
which is necessary for releasing the adhesive tape from the adhesive joint
(stripping force). If the stripping force is greater than the tearing
resistance of the adhesive tape, the adhesive tape tears during the
releasing process.
Interesting applications of previously described self-adhesive tapes
comprise, inter alia, use in adhesive hooks, such as are frequently used
domestically in bathrooms and kitchens (see DE 42 33 872, WO 94/21157,
U.S. Pat. No. 5,507,464) or else specific adapter systems. Commercially
available in this respect are, inter alia, adhesive hooks of modular
construction (tesa Power-Strips System Hooks), comprising a base plate to
which the hook body is adapted. Corresponding base plates thereby allow
mouldings of the widest variety of formations to be adapted, permitting a
wide range of variations of applications. Examples comprise adapters for
the fixing of cables, mirrors, pictures etc.
What is disadvantageous about the previously known problem solutions is
that the releasing of the adhesive bond has to take place by pulling the
adhesive strips substantially in the bonding plane. Errors in use are
consequently inevitable for the inexperienced user. If the adhesive tape
is pulled off at a significant angle with respect to the bonding plane or
even perpendicularly forwards, the additionally occurring frictional
forces and the additional contact pressure between the adhesive tape and
the object to which it is adhesively bonded, or the base plate used, may
cause tearing of the adhesive tape in the region of the pulling-off edge
of the adhesive film. The tearing resistance relevant here is not
identical to that determined in accordance with DIN 53504 in the tearing
force/ultimate elongation experiment. Rather, owing to the pulling out of
the adhesive films from the adhesive joint at an angle other than
0.degree., it is at usually considerably lower values. Increasing the
tearing resistances of the adhesive tapes used is one possible way of
reducing the tendency to tear. However, a corresponding measure is often
only possible to a limited extent, since it (for example the use of
thicker self-adhesive tapes or more tear-resistant intermediate
substrates) cannot be carried out selectively without adversely
influencing other product properties, such as for example the
extensibility.
Tearing of the adhesive tape may likewise occur if the stretching of the
adhesive tape is performed, as intended, substantially in the plane of the
adhesive bond and in the direction of the grip. In many case it has been
found that tears are caused in this case by the user exerting very
considerable force to press the item to be released perpendicularly
against the object to which it is adhesively bonded during the releasing
process. As a result of this also, the force necessary for pulling the
adhesive tape out of the adhesive joint is increased to such a great
extent that the tearing resistance is exceeded, with the unfortunate
consequence for the user that the adhesive tape tears and the adhesive
bond can no longer be released non-destructively and without leaving any
residue.
And finally there are many applications in which, for reasons of spatial
limits, pulling in the direction of the bonding plane is not possible, for
instance because the adhesive bonding was performed in a depression or in
a corner.
The object of the present invention was to overcome the aforementioned
disadvantages.
SUMMARY OF THE INVENTION
This is achieved according to the invention by a device such as that
described in more detail in the patent claims.
Thus, the invention relates to a redetachable, self-adhesive device having
a plate, the sides and/or front side of which have fastening means, if
appropriate, and the rear side of which has a strip of an adhesive film
which is adhesive on both sides and is adhesively attached in such a way
that one of the adhesive film protrudes beyond the plate as a grip, the
adhesive film being of such a kind that the adhesive bond achieved with it
can be released again by pulling, stretching the strip, characterized in
that the plate (1) has at its end, or on its rear side (2) at least in the
region (3A, 3B) which bears against the grip (6) of the adhesive film
strip (5), low stick and slip friction with respect to the adhesive film
strip (5).
Preferred in this case is a device in which the stripping force at a
pulling-off angle of 60.degree. is no more than three times, preferably
two times, the stripping force at the pulling-off angle of 0.degree..
Particularly preferred in this case is a device in which the stripping
force at a pulling-off angle of 90.degree. is no more than three times,
preferably two times, the stripping force at the pulling-off angle of
0.degree..
Preferred is, furthermore, a device in which the region (3A, 3B) which
bears against the grip (6) allows moreover with respect to the adhesive
film strip a stripping force at a pulling-off angle of 60.degree. which is
three times the stripping force at the pulling-off angle of 0.degree.,
preferably two times the stripping force at the pulling-off angle of
0.degree..
Particularly preferred is, furthermore, a device in which the region (3A,
3B) which bears against the grip (6) allows moreover with respect to the
adhesive film strip a stripping force at a pulling-off angle of 90.degree.
which is three times the stripping force at the pulling-off angle of
0.degree., preferably two times the stripping force at the pulling-off
angle of 0.degree..
Preferred is, furthermore, a device in which the region (3A, 3B) which
bears against the grip (6) has a low-energy surface, based on
fluorine-containing polymers, organo-silicon polymers, polyolefins or
based on polymers which contain fluorine-containing segments, segments of
organo-silicon polymers or polyolefin segments or those based on a mixture
of the aforementioned polymers, if appropriate with further polymers.
Preferred is, furthermore, a device in which the region (3A, 3B) which
bears against the grip (6) has a surface tension of up to 37 mN/m.
Preferred is, furthermore, a device in which the region (3A, 3B) which
bears against the grip (6) is formed together with the plate (1) as an
integrated injection-moulded part of plastic.
Preferred is, furthermore, a device in which the adhesive film, with or
without an intermediate substrate, is elastically or plastically
extensible.
Preferred is, furthermore, a device in which the adhesion of the adhesive
film is less than the cohesion, the adhesiveness is to a great extent
dissipated when the film is extended, and the ratio of pulling-off force
to tearing load is at least 1:2.0, in particular 1:3.0, the adhesive film
being of the kind which is based on thermoplastic rubber and tackifying
resins, with high elasticity and low plasticity.
Preferred is, furthermore, a device in which the rear side of the adhesive
film (5) is covered with a release laminate, such as a siliconized release
paper or a release film.
Preferred is, furthermore, a device in which there is a hook on the front
side of the plate (1).
Preferred is, furthermore, a device in which the plate (1) has on its rear
side (2) laterally alongside the adhesively attached adhesive film strip
(5) spacers (8A, 8B), the height of which is less than the thickness of
the adhesive film strip (5).
Preferred is, furthermore, a device in which the spacers (8A, 8B) are
located on both sides alongside the adhesively attached adhesive film
strip (5).
Preferred is, furthermore, a device in which the spacers (8A, 8B) are
formed as fillets or segments.
Preferred is, furthermore, a device in which the spacers (8A, 8B) are
formed together with the plate (1) as an injection-moulded part.
Preferred is, furthermore, a device in which the height of the spacers (8A,
8B) is 30-90% of the thickness of the adhesively attached adhesive film
strip (5), in particular is 0.3-0.6 mm with a thickness of the adhesive
film strip (5) of 0.65 mm.
Moreover, the invention relates to the use of a plate for such a device for
redetachable, self-adhesive fastening and releasing again by pulling on
the grip of the strip at an angle approximately perpendicular to the
bonding plane, in particular at such an angle of 45.degree.-135.degree.
with respect to the bonding plane.
DETAILED DESCRIPTION OF THE INVENTION
The height of the spacers is advantageously chosen such that it is less
than the thickness of the adhesive film (unstretched), so that a
satisfactory adhesive bond with the adherent surface is possible. The
extension of the adhesive film occurring during the detachment operation
causes the said film to be reduced correspondingly in width and thickness.
If the thickness of the adhesive film reached during detachment is less
than the height of the spacers, detachment of the adhesive film without
tearing is even possible if high contact pressures occur at the same time
vertically to the adhesive bond, which would otherwise have lead to
tearing of the adhesive tape.
The use of plates which, on the grip side, in the edge region of the
adhesive bond, contain a material which has a lowest possible coefficient
of stick friction and a low coefficient of slip friction with respect to
the adhesive film respectively used make it possible for the adhesive bond
to be released without leaving any residue even if the angle between the
bonding plane and the pulling-off direction is significantly greater than
0.degree., in particular about 45-135.degree., in particular
60-100.degree..
Particularly advantageous in this case is a combination of these elements,
in other words a plate with a region of low stick and slip friction at the
end over which the adhesive film strip is to be pulled, and provided with
spacers to the sides of the adhesively attached adhesive film strip in
order to permit easy, non-tearing pulling off of the adhesive film strip
even when excessive pressing force is being applied to the plate during
the said pulling off.
Since the user of a plate according to the invention possibly does not
realize over which of its ends he is to place the adhesive film strip with
its grip protruding, in order to pull it off later over this edge, such a
region is advantageously provided at both ends of the plate. In the case
of such a symmetrical design, the user does not have to concern himself in
this respect.
A further advantageous possibility is for a plate according to the
invention which has merely one edge region with low stick and slip
friction to be designed in such a way that the same region can easily be
differentiated visually by its optical appearance, for instance its
colour, from the edge lying opposite it, which does not have a
correspondingly low stick and slip friction.
According to the invention, suitable in particular as adhesive films are
those corresponding to DE 33 31 016, DE 42 22 849, DE 42 33 872, WO
92/11333 and WO 94/21157.
For instance, DE 33 31 016 A1 describes an adhesive film for re-releasable
adhesive bonds which allows an adhesive bond established therewith to be
releasable by pulling on the adhesive film in the direction of the bonding
plane. With such adhesive films, high adhesive forces and shear strengths
can be achieved and adhesive bonds can be released again without further
aids, in a way comparable to the opening of a preserving jar, similar to
the way in which there the rubber seal is pulled by the grip out of the
seal joint.
DE 42 22 849 C1 describes such an adhesive film with a UV-impermeable grip.
WO 92/11333 also describes, inter alia, adhesive films for corresponding
applications, the adhesive films used having a low elasticity with at the
same time high extension.
Double-sided self-adhesive tapes with a foam intermediate substrate, for
example of polyethylene foam, can also be used according to the invention.
In general, for production, processing and handling of the particularly
preferred adhesive films, reference is made to DE 33 31 016, DE 42 22 849
and WO 92/11333.
Suitable as the material for the plate or moulding, in particular as base
plates, are plastic, metal, wood (coated, for example painted, and
uncoated), ceramic and the like. In particular, the plate itself may be
formed from a material which has a low stick and slip friction with
respect to the adhesive films used.
Reduction of Stick and Slip Friction and Adhesive Interactions between the
(Base) Plate and Adhesive Film during the Redetachment Process
Mouldings or (base) plates according to the invention serve for receiving
one side of the adhesive film, the other side of which is adhesively
bonded onto the selected underlying surface. A wide variety of adapters,
including hook bodies, can be placed onto the base plate. The plate may,
however, also be designed itself as a hook or the like, in other words
have for example a hook-like holding device on its front side. To produce
a high bonding strength, the surface of the base plate on the side to
which the adhesive film is applied consists in particular of a material
which has an adhesion with respect to the adhesive film which is adequate
for the respective application. When using contact adhesives based on
styrene block copolymers or acrylate copolymers, advantageously used in
this case are, in particular, polystyrene, impact-modified polystyrenes,
PMMA, aromatic polyesters, polycarbonate or polyamides, including
aromatic-containing polyamides. Base plates according to the invention are
modified at at least one edge (over which the detachment process later
takes place) in such a way that the edge region consists of a material
which has low stick and slip friction coefficients with respect to the
adhesive film used, which generally corresponds to a low adhesion of the
adhesive films to this region. The friction coefficients are in this case
to be set such that, under the given test conditions, the sum of the
stripping force and frictional force is lower than the tearing force of
the adhesive films used even at pulling-off angles significantly above
0.degree. from the underlying surface. An adequate reduction of the
frictional forces is achieved, for example, by the edge region of the base
plate being formed by a low-energy plastic surface. Suitable materials
which can be used are, inter alia, fluorine-containing polymers, in
particular perfluorinated polymers, for example poly(tetrafluoroethylene),
organo-silicon polymers, for example poly(dimethylsiloxane), polyolefins,
for example poly(ethylene), in particular high-density poly(ethylene),
which have in particular surface tensions of .ltoreq.about 37 mN/m.
Suitable with preference are strong materials which deform little during
the detachment process. In addition to the polymers mentioned above,
suitable are those polymers which contain fluorine-containing segments,
segments of organo-silicon polymers or polyolefin segments. Furthermore,
mixtures of the aforementioned polymers and blends of the aforementioned
polymers with further polymers may also be used.
In the case of injection-moulded articles, providing one edge of the base
plate with one of the aforementioned materials can take place by taking
corresponding steps during the injection moulding of plastic bodies (use
of a plurality of polymers in the injection-moulding process; 2-component
injection). Another possibility is the subsequent application of a plastic
in the form of a suitable moulded part in the edge region of the base
plate. A further possibility is offered by the subsequent coating of base
plates in the edge region by means of one of the polymers mentioned above.
Coating possibilities comprise coating from solution, dispersion or as a
100% system from the melt. Optionally, the coated materials may be
subjected to subsequent crosslinking.
Conversely, a plastic which has low friction coefficients or low adhesion
with respect to the adhesive films used may be chosen as the base plate
material itself. If need be, the corresponding base plate may be designed
or treated in such a way that high adhesion with respect to the adhesive
film, and consequently high adhesive forces, shear strengths and
traction-adhesive strengths, are made possible in the bonding region of
the adhesive film, but not in the edge region over which the detachment of
the adhesive film takes place. Corresponding pretreatment methods may be,
for example, flame treatment, corona and plasma treatment, gas-phase
fluorination or else a wet-chemical pre-treatment method. Optionally,
treatment of the surface with a primer is additionally possible.
According to the invention, a low friction coefficient between the adhesive
film and the edge of the base plate can also be achieved by incorporating
a rotatable roller or fitting a plurality of rotatable balls in a row into
the end of the base plate (utilizing the rolling friction). However,
corresponding solutions generally appear to be more complicated, and
consequently economically of less interest, than the method described
above.
Improving the Detachability by Spacers Integrated into the Base Plate (into
the Moulding)
To accomplish a pulling-off behaviour without tearing, even under the
effect of high forces acting perpendicularly with respect to the bonding
plane (for example caused by high contact pressure when releasing the
adhesive bond), the moulding or the base plate is preferably equipped with
spacers (for example fillets) on the side which bears the adhesive film.
Spacers may be provided on both sides alongside the adhesive film over the
entire length of the base plate, or else only in certain subregions
thereof. Specific formations, right-angled fillet-like, rounded-off
fillet-like, punctiform etc., are possible.
Tests with different redetachable adhesive films show that, depending on
the type and structure of the adhesive films used, typical stripping
extensions lie between 100% and 800%. In practice, it is found that, in
the case of substantially rubber-elastic adhesive films, the height of the
spacers should be at least about 0.05 mm, preferably 0.10 mm, higher than
the thickness of the stretched adhesive films during the detachment
process. For a reliable adhesive bond, on the other hand, the spacer
height should be kept about 0.05 mm, preferably 0.1 mm, particularly
preferably 0.15 mm less than the thickness of the adhesive films in the
non-stretched state. The values specified relate to planar solid adherent
surfaces. In the case of rough and/or easily deformable adherent surfaces,
values higher than those quoted may be advisable both for a satisfactory
bonding process (adequate contact pressure) and for satisfactory
redetachment.
BRIEF DESCRIPTION OF THE DRAWINGS
The invention is to be explained below with reference to examples and
figures, without however wishing to restrict it unnecessarily.
In the drawing:
FIG. 1 shows an obliquely lateral view of a plate according to the
invention,
FIG. 2 shows a side view according to FIG. 1, with an adhesively attached
adhesive film strip,
FIG. 3 shows an obliquely lateral view of a further plate,
FIG. 4 shows an obliquely lateral view of yet another further plate, and
FIG. 5 shows a front view of a plate according to FIG. 4.
To be specific, FIG. 1 shows a plate (1) with laterally arranged engagement
devices (4) which can engage in corresponding engagement devices of a part
to be attached, for instance a hook or the like, as is commercially
available as the system hook for "tesa.RTM. Power-Strips". The rear side
(2) of the plate (1) serves for adhesively attaching the adhesive film
strip (5) (FIG. 2), the regions (3A) and (3B) of this rear side (2) which
bear against the grip (6) of the adhesive film strip (5) consisting of a
material of lower stick and slip friction with respect to numerous contact
adhesives, in this case of high-density polyethylene. Since the user can
stick the adhesive film strip (5) onto the plate (1) in such a way that
the grip (6) can protrude both at one end and at the other end, both
regions (3A) and (3B) are designed such that these regions have low stick
and slip friction or adhesion with respect to the adhesive films used.
FIG. 2 shows the plate (1) with an adhesively attached adhesive film strip
(2), the grip (6) of which is covered non-adhesively with thin films (7).
In FIG. 3, a different embodiment is shown, in which the plate (1) exhibits
a rear side (2) which serves for receiving an adhesive film strip (not
shown) and which has at both ends regions (3A) and (3B) which consist of
high-density polyethylene. The plate (1) also has engagement devices (4),
as according to FIG. 1.
FIG. 4 shows a further preferred embodiment of a plate (1) with a rear side
(2) which serves for receiving an adhesive film strip (not shown) and
which is provided, in a way corresponding to FIG. 3, with regions (3A) and
(3B) of high-density polyethylene and also engagement devices (4). In
addition, the plate (1) has, however, on both sides of the rear side (2)
spacers (8A) and (8B), formed as fillets, the height of which is about
half the thickness of the adhesive film strip to be applied, the spacing
of the spacers (8A) and (8B) being chosen such that the adhesive film
strip can easily be placed widthwise in between, as shown in the front
view according to FIG. 5, with the plate (1) and region (3A) at the end
face, engagement devices (4) and spacers (8A) and (8B), and also an
adhesive film strip (5) placed in between.
EXAMPLE 1
Adhesive films described in Example 2 are applied to spacerless base plates
of the dimensions 3 mm.times.40 mm.times.20 mm consisting of polyethylene
(PE 300; from Arthur Kruger), Styroblend KR 2776 (BASF), polystyrene
(Vestyron 214; Chemische Werke Huls) and steel, and then the test pieces
thus obtained are fixed on a planar underlying steel surface. The
preparation of the test pieces corresponds to that of Example 2. For
redetachment, the base plates are held on the underlying steel surface by
a test person using his thumb and fingers on the side on which the grip
protrudes, as far as possible without applying pressure, after which the
adhesive film strips are slowly pulled out from the adhesive joint at
different angles. The separation rate is about 1000 mm/min. It is tested
whether the adhesive films can be released from the adhesive joint without
tearing.
______________________________________
Surface Can be detached without tearing/stripping
Base plate
tension* force in N/cm at a pulling-off angle of
material
in mN/m about 5.degree.
30.degree.
60.degree.
90.degree.
______________________________________
Polyethylene
<34 yes/9 yes/12 yes/14
yes/15
Styroblend
about 36 yes/9 yes/12 yes/15
yes/21
KR 2776
Polystyrene
about 36 yes/10 no/>25 no/>25
no/>25
Steel -- yes/10 yes/17 yes/23
no/>25
______________________________________
*corresponding to DIN 53364
If polyethylene and Styroblend KR 2776 are used as the base plate material,
redetachment of the base plates without tearing is possible in the case of
all the pulling-off angles tested here.
EXAMPLE 2
For a single-layer adhesive film of the following formulation:
50 parts of Foralyn 110 (Hercules), 50 parts of Vector 4211 (Exxon
Chemical), 0.5 parts of Irganox 1010 (Ciba)
of a thickness of 650 .mu.m, a maximum tensile force of 52 N/cm,
corresponding to 8.0 MPa, and an ultimate elongation of 1300% are
determined.
Rectangular pieces of the adhesive film measuring 20 mm.times.50 mm are
adhesively bonded centrally to base plates consisting of steel of the
dimensions 3 mm.times.40 mm.times.22 mm (height.times.length.times.width)
in such a way that the base plates are covered on one side over their
entire length with the adhesive film and a 10 mm long strip of adhesive
film protrudes beyond one of the short sides of the base plates, which can
be used as a grip for later detachment. The base plates are provided on
both longitudinal edges on the side to which the adhesive films are
applied with spacers 0.5 mm wide and of different heights. The base plates
provided with adhesive films are adhesively bonded onto a planar
underlying surface of Resopal. For this purpose, the base plates provided
with the adhesive films are applied flatly to the underlying Resopal
surface and are pressed onto it with 500 N for 5 seconds. In a second
operation, for detaching the adhesive films, the test pieces fixed in this
way are subjected to a force of likewise 500 N, acting vertically onto the
bonding plane, and then the adhesive film strip is pulled out of the
adhesive joint at an angle of <10.degree. with respect to the bonding
plane. For comparison, the tests are carried out without any force acting
vertically on the bonding plane. The stripping rate in all the tests is
about 1000 mm/min. The following results are obtained:
______________________________________
Vertical pressing
Without vertical
Height of the spacers
force 500 N force
______________________________________
No spacer Strip tears Can be detached
without tearing
0.3 mm Can be detached
Can be detached
without tearing
without tearing
Stripping force*
10//14 N/cm
0.4 mm Can be detached
Can be detached
without tearing
without tearing
Stripping force*
9//15 N/cm
0.5 mm Can be detached
Can be detached
without tearing
without tearing
Stripping force*
9//10 N/cm
0.6 mm Can be detached
Can be detached
without tearing
without tearing
Stripping force*
9//10 N/cm
0.7 mm No adhesive bonding
No adhesive bonding
possible possible
______________________________________
*Mean value//maximum value (the maximum value is reached at the end of th
stripping operation).
Under the chosen test conditions, only base plates provided with spacers
can be detached again without tearing under the effect of high vertical
forces acting on the base plate.
EXAMPLE 3
Base plates corresponding to Example 1, with a spacer height of 0.5 mm, are
modified in such a way that a rectangular metal piece 1 mm deep and of the
same width is milled out at the edge over which the adhesive films are
detached. A piece of plastic, of PTFE, polyethylene (PE 300; from Arthur
Kruger), Styroblend KR 2776 (BASF), polyamide (Ertalon 6 SA, from Arthur
Kruger), measuring 0.7 mm.times.1 mm.times.20 mm
(height.times.width.times.depth), or a siliconized release paper (Natrosil
20 291; Schleipen & Erkens), measuring 0.12 mm.times.1.5 mm.times.20 mm
(height.times.width.times.length), is adhesively fixed in the depression.
The following preparation of the test pieces corresponds to that of
Example 1. In a way corresponding to Example 2, it is tested whether the
adhesive films can be pulled out of the adhesive joint without tearing.
However, during the releasing operation, the base plate is not kept in a
stress-free state, but instead, as in Example 1, a force of 500 N is
applied to the test pieces vertically onto the bonding plane.
______________________________________
Surface Can be detached without tearing/stripping
Base plate
stress*
force in N/cm at a pulling-off angle of
edge material
in mN/m about 5.degree.
30.degree.
60.degree.
90.degree.
______________________________________
PTFE <30 yes/9 yes/10
yes/11 yes/12
Polyethylene
<34 yes/9
yes/13
yes/15
Styroblend KR
about 36 yes/9 yes/14
yes/20
2776
Polyamide about 42
yes/9 yes/16
no/>20
Siliconized
<30 yes/9
yes/18
yes/23
release paper
Steel --
yes/9
yes/20
no/>25
For comparison: Base plate edge material = base plate core
material = polystyrene
Polystyrene
about 38 yes/10 no/>25
no/>25 no/>25
______________________________________
If materials with low-energy surfaces are used, pulling out from the
adhesive joint without tearing is possible in the entire range of
pulling-off angles under consideration.
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